The NRMA is outside waiting to fix my car but I'm not leaving my laptop. Amateo from Athens has just scored 155 points with "zapateo" and Chuan from Shanghai wants to know why I wasted my blank on "moan". Kweku from Harare has nudged me 10 times and is threatening to forfeit. And Mike from Tupelo, who sits on the formidable score of 2899, is being a gent and not forcing me to play my last "i" on "tit" even though he'll destroy me when I do.

These are the strangers I spend my nights with, addicts from Brazil to Jakarta to Los Angeles, who are hooked on Mattel's online Scrabble game. They are CEOs, homemakers, IT programmers, oil sheikhs, backpackers and, possibly, criminals. My only clue to their real identities are the photos that pop up each time we play - showing them with lovers and pets, smiling in Doha boardrooms, on Phuket beaches and Beijing building sites. Our furious competition to rise to the top of the leader board is so consuming, if we stay away even for an hour, Facebook floods our feeds with nudges.

Free online gaming is a booming and lucrative phenomenon. According to Deloitte's 2014 technology spotlight review, the "freemium" model - in which players access games for free, but can buy virtual currency, goods and add-ons to unlock levels and enhance their experience - is "a rapidly expanding niche" in the online and mobile gaming industry.

I want candy: A scene from Candy Crush Saga.

In the first quarter of this year, 90 per cent of Google Play's revenue came from the 1.5 million-plus games it hosts online. But the money is not being made from games you pay for upfront. A report by US-China business analyst App Annie shows that by May 2014, revenue from freemium apps had grown to a staggering 98 per cent of Google Play's total worldwide revenue.

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Clearly, something is going terribly right for the designers of the seductively fun, fiendishly addictive smorgasbord of puzzle, fantasy and gambling games now on our screens.

As one of 500,000 Facebook Scrabble addicts, I hide my habit by blocking Mattel's updates from my timeline and ignore prompts to buy "super cool snow" tiles and ad-stopping boosters. But I am a minority. Gamer sites are full of desperate confessions - mums who've scrimped on toddlers' meals to play Candy Crush; commuters who've sprained ankles boarding trains while buying power-ups for Fruit Ninja; students who've quit their degrees to finance riot points on League of Legends.

A scene from Farmville 2.

The games on offer feed every possible taste. Hentai fans can slap cartoon bottoms in Spank Beauty Booty; soccer nuts can be heroes on FIFA Soccer; lovers of the film Despicable Me can play spin-off Minion apps; Jane Austen devotees can swap witticisms with Mr Darcy in Austen Unbound; Beliebers can give the pop star a haircut in Justin Beard Salon; and gore addicts can unleash their inner killer everywhere from Warfare 1944 and Bloody Rage to Mass Mayhem Zombies. There's even a game for necrophiliacs - in Gibbets, you can shoot the ropes of dying people as they hang.

The mega Godzilla of them all is Candy Crush Saga. A match-three puzzle game launched by UK-Swedish company King Digital Entertainment in 2012, Candy Crush Saga has 61 million Facebook likes and an estimated 500 million users around the globe. King earns more than $800,000 in daily revenue and $2 billion in sales, with 150 billion games being played to date. With 60 per cent of UK commuters playing it to and from work, 93 million people navigate the game's exploding sugar bombs every day. One in seven play it in Hong Kong. In March this year, King's initial public offering saw the company valued at $7.08 billion.

So phenomenal is Candy Crush's ability to keep users hooked, it prompted the UK Office of Fair Trading to push for guidelines on games with exploitative mechanics and compelled the founder of online games company Six to Start, Adrian Hon, to call for a "fact box" on the landing page, warning users how much time and money they're likely to spend, the same way nutrition charts rate food.

A scene from online game Criminal Case.

A 2013 survey of 1000 Candy Crush players found 32 per cent ignored family to play the game, 28 per cent played during work, 10 per cent argued with partners about it and 30 per cent admitted they were "addicted." So why the pull? Candy Crush is just a grid of moveable candies, with deceptively hokey graphics. But Candy Crush, and a million other freemium games vying for our cash, has been carefully designed to keep us playing.

Studies on game addiction speak of the positive reinforcement loop: repetitive tasks that, once completed, give us a pleasurable reward - much like B. F. Skinner's self-feeding lab rats. With multiplayer games, there's the added attraction of beating others in a virtual, and safely anonymous, world; single-player games promote a sense of community through Facebook and Twitter.

I am your usual time-poor, bill-rich city dweller. My Scrabble habit may be embarrassing, but it's not yet a liability - the NRMA only had to text me once to get me off my screen and out the door. But do I have the discipline to resist five of the world's most addictive online games? Will I be so hooked that I cancel my life? Will my credit card be safe? Bring it on, freemium. My trigger finger's on the mouse. Let's play.

1. CANDY CRUSH SAGA

Game type: Match-three puzzle

Daily Active Users: 43,702,752 on Facebook

Addiction rating: 10/10

With its ye-olde-worlde candy store, hypnotic music and luscious treats, candy town looks a lot like my inner-five-year-old's perfect world. I can feel my dopamine levels rise as I match the shiny candies and watch chocolate freckles explode in a sugary haze.

Designed with women aged between 25 and 45 in mind, Candy Crush ticks all the boxes: the Willy Wonka topography (butterscotch boulders, lemonade lake) brings back feel-good childhood memories; the pigtailed heroine Tiffi is just plump enough to keep weight-anxiety at bay; the obstacles (chocolate spawner, candy bombs) constantly change to keep you engaged; and when you defeat them, a sexy James Brown voice croons sweet nothings such as "Delicious!" and "Sugar crush!" in your ear.

The game - played by 93 million people worldwide - strikes the perfect balance between difficulty (each level is harder, conveying a sense of achievement when you beat it) and pleasure.

The nostalgic music, the "sugar-hit" of those exploding candy bombs, the kitsch animations that distract you as the next level loads, all immerse you in a positive, unthreatening world. The catch is, you only get five lives. And each new level is just difficult enough to not master in one go.

To keep playing, you must either wait for your lives to replenish (up to four days), ask your Facebook friends for new ones (deeply uncool) or buy them. It costs $1.10 for 10 and it's easy: once the app has your credit-card details it renews you with a single click. You don't even have to think about the fact that you're paying some gazillionaire for the infantile pleasure of moving lollies around a cartoon grid. So far, I've spent $17.60. And I'm on level 205.

2. FARMVILLE 2

Game type: Simulation

Daily Active Users: 4,581,010 on Facebook

Addiction rating: 1/10

There's a reason someone's put up a Facebook post suggesting you de-friend "anyone who still plays FarmVille". It's daggy. Released by Zynga in 2009, FarmVille was once the No. 1 game on Facebook. In the first quarter of 2012, the game and its spin-offs, CityVille and FrontierVille, generated $329 million. Now FarmVille 2 has slipped to 44, surpassed by Finnish designer Supercell's Hay Day. Hay Day is built primarily for mobiles and is fiddly to access on a Mac. As a gaming addict I want my hit now, in one click. I start to download the Hay Day APK file and Marie from FarmVille 2 suddenly pops on my screen, introducing herself as my "country cousin" and welcoming me back to the "old Broinowski Farm". The personal touch and laid-back guitar is hard to resist. I'm in.

Marie is a busy little avatar. She trots around my meadow, showing me how to plant tomatoes, harvest hay and feed the goats. There's a roadside stall where I can turn my produce into virtual coins and clickable fountains to water my crops.

There's a cabinet of objects I can craft with things I grow, including apple pies, jams, and inexplicably, a US Democrat or Republican election pin. The pressure to reap and sow so I can keep on feeding those pesky animals is relentless, and all too soon my cash runs out.

"I can clear space for expansion," suggests Marie helpfully, pointing me to PayPal. She's already blasted my Facebook with triumphant announcements that Anna is "GOOD AS GOLD!" and Anna just "PLOUGHED HER PROFITS!" So far, 20 people have de-friended me.

If you fantasise about having a tree-change or getting into sustainable gardening, FarmVille 2 is great - but I want to string Marie and her squawking chickens up on Gibbets. I'm outta here.

3. CRIMINAL CASE

Game type: Hidden object

Daily Active Users: 4,934,991 on Facebook

Addiction rating: 7/10

Designed by French developer Pretty Simple, Criminal Case exploits the forensic appeal of TV crime series such as NCIS and Bones. A spunky detective inducts you into the murder investigation unit of a generic American city, helping you customise your avatar's gender and clothes. Then he introduces you to the hipster African-American autopsy guy, the straight white police chief and your first case. Rosa Wolf, curvy and blonde, lies garrotted in a garbage dump. Your mission is to find six pieces of "evidence" buried in the frame. Freemium is full of hidden-object games, from Hidden Express to Little Shop of Treasures.

What sets Criminal Case apart is the way it mixes up different tasks in an immersive story world. The suspects and victims all have distinct (albeit stereotypical) personalities, and the game's noirish soundtrack and slick animations ramp up the urgency as you piece together body parts, interview witnesses and analyse blood samples to catch the killer.

I'm more of a Breaking Bad fan than a CSI one. I prefer cynical dialogue over cookie-cutter plots, but this take on the crime format has sucked me in. The flashbulb swoosh when you get something right is addictive and each murder scene is beautifully painted, like a grotesque Norman Rockwell.

It's seductive to suddenly have a brand-new job, with cool-looking colleagues who carry guns and say things like, "Nice work, officer Anna" when you arrest some toothless guy. But 10 minutes in, the game hits me up for my credit card. Real Estate Thug is in the line-up and I'm about to convict him - the perfect cliffhanger for my "energy" to suddenly run out. My partner, full of concern, tells me to buy virtual food: $6.99 for a 2D burger you can't even taste? Meh.

4. TEXAS HOLD 'EM POKER

Game type: Cards and gambling

Daily Active Users: 3,143,799 on Facebook

Addiction rating: 6/10

Before the landing page has loaded, you want a martini. Zynga's portal is all red velvet and clinking casino chips: it smells of money. Once in, you sit down with eight gamers from around the world, playing in real time.

A sexy croupier deals your first card and you can either buy in or fold. The next four deals proceed like standard five-card stud - you bet and raise based on your own hand and that of the house.

As a Texas Hold 'Em virgin, I receive $55,000 in virtual chips to start the game, but it is too fast to track. My competitors have already raised and checked before I can even read the explanatory "dealer chat" scrolling on the side. I'm sitting on a pair of bullets, but am too slow to call.

Freemium poker is lucrative and booming: players who rise to the top online can enter real-world satellite tournaments which feed into World Series Poker. When 2003 World Series Poker winner Chris Moneymaker made the transition in 2003, revenue from online poker tripled in a year. Now, Zynga's first quarter takings for 2014 sit at $168 million, 24 per cent of which comes from online poker.

I can see why. It is deliciously illicit to take money off strangers who don't know your name. The good-luck pizza and crown charms adorning the players' name tags gives the game a homely feel.

But when I next try to have a crack, Zynga demands $1 for 512,500 chips to buy back in. If I wasn't on a deadline, I'd pay. As it is, I switch to the safer, non-gambling option of Pyramid Solitaire. And when the 1930s adventuress suggests I buy an "unlocker" to get deeper inside the pyramid, I quit.

5. DRAW SOMETHING

Game type: Multiplayer

Daily Active Users: 255,241 on Facebook

Addiction rating: 10/10

Addiction is a personal thing. There are a thousand wildly popular candidates for this last spot, from Angry Birds and Clash of Clans to the freemium version of Minecraft.

But I am totally addicted to Draw Something. Once massive (15 million daily users in 2012) and now a cult oddity, this multiplayer game has shown me the joy of being a 15-year-old male.

The signature game of developer OMGPop (which Zynga snapped up for $200 million two years ago), Draw Something is simple but brilliant. Players sign in with aliases (mine is DaliDoesElephantz) and join an animated chat room, where each person draws a picture of a word while the others try to guess it.

Writing is cheating but that's irrelevant. To most players, the fun comes from participating in the simultaneous commentary the drawings trigger.

I've drawn earmuffs, igloos and pots of gold with horny adolescents ("Who wants SEX?"), Taiwanese students ("I'm crap at this LOL") and Saudi housewives ("Wots ur name Dali? In my lang its rude").

I know that most are aged under 20 because when I draw a typewriter no one gets it. The majority draw stick figures but once in a while, an extraordinary artist such as Zarmina1 appears, whose sketches are almost as exquisite as Albrecht Dürer's.

The chat function continues between games, so you can actually bond with your co-players. The matey kudos I get from the boys ("U rock Dali. U DA KING") is oddly satisfying. But the real delight comes from telling Zarmina1 about the Spanish artist Salvador Dali, whose ability she shares, but whom she has never heard of.

As she creates another masterpiece and the game congratulates her in its weird slang - "FoShizzlemyNizzle thats butts!" - I tell Zarmina1 to check out Dali's melting clocks on Google.

She does, and flashes me a winking gold smiley face. Online, that's close to love.